Are all wild （野生的） animals always dangerous?

    {#blank#}1{#/blank#} of people think that all wild animals are{#blank#}2{#/blank#}. But, in fact, few of {#blank#}3{#/blank#} will eat man if he leaves them alone（不招惹它们）. If you meet a lion, I think you will run away, but even a lion will avoid（避免） a man if it {#blank#}4{#/blank#} very hungry. Lions only kill and eat men when they are too old{#blank#}5{#/blank#} their food, such as sheep and other animals.

    We know some animals even are afraid of {#blank#}6{#/blank#} when they happen to（碰巧） see men. Some of them stand and look at a man for some time before they run away. The others {#blank#}7{#/blank#} care of him at all, but they walk {#blank#}8{#/blank#} in another direction. Wild animals only eat a man when they are afraid that the man {#blank#}9{#/blank#} to kill their young babies, or a man is shooting（开枪） at them and they are made angry

    Next time you go to the park, please watch some animals such as tigers, lions and {#blank#}10{#/blank#} in the cages. You can find they don't attack（攻击） people if you don't make them angry.

    The cloth tiger{#blank#}1{#/blank#}popular since the ancient times of China. During the Spring Festival, it's more popular{#blank#}2{#/blank#}the cloth tiger for children to bring them health. Most of them are made by the smart country women. They have created the cloth tigers in different kinds of shapes with different materials. The cloth tigers usually {#blank#}3{#/blank#}large bodies and look very nice.

    People believe that a cloth tiger can keep the whole family safe, so it {#blank#}4{#/blank#}"Tiger for Protecting House". My best friend's birthday is coming. I{#blank#}5{#/blank#}her a red cloth tiger. I think she may like it.

A Cloud of Hope and Danger

    In 2050, a small cloud floats through the air in a hospital operating room (手术室). In the room a patient, suffering from cancer, lies on a table. The cloud surrounds (包围) the patient, {#blank#}1{#/blank#} her body and filling her lungs (肺). The cloud is not smoke or steam. It is made of millions of microscopic robots {#blank#}2{#/blank#} nano-robots (纳米机器人). These tiny robots move from cell (细胞) to cell in the patients' body, destroying the cancer cells.

    Fighting cancer with nano-robots is only an idea today, {#blank#}3{#/blank#} scientists say that it would be possible in the future. Using nano-robots for good purposes such as fighting disease or repairing the environment may be the {#blank#}4{#/blank#} to many of today's problems.

    However, nano-robots could be a {#blank#}5{#/blank#} risk as well. Since nano-robots are so tiny, they will have to work in large teams of many thousands to 'many millions. {#blank#}6{#/blank#} this reason, nano robots will have to be programmed to build {#blank#}7{#/blank#}. Scientists will not have the ability to build millions of nano-robots one by one.

    This ability to reproduce (复制) is making some scientists worried. What if something goes wrong in the programming? Quite a lot of crazy nan-orobots would be far {#blank#}8{#/blank#} than any disease. Some people think that if they get out of control, nan-orobots could destroy the Earth.

    What should be done? Should we continue {#blank#}9{#/blank#} nan-orobots or should we search for other methods? This is one of the many difficult {#blank#}10{#/blank#} that we have to make in the future.